Simulation on thermoelastic stress field and laser ultrasound waveform in non-metallic materials by using FEM

The thermoelastically generated stress and ultrasound fields in non-metallic materials by laser illumination are presented by using finite element method (FEM). The model accounts for the effects of thermal diffusion and optical penetration, as well as the finite width and duration of the laser source. The numerical results show that the strength and feature of the force source can be related to the heat input and certain material properties. The relationships between the stress waves and the ultrasound waveforms, particularly the precursor, are analyzed. The typical surface acoustic waves (SAWs) and the bulk waveforms at the epicenter are presented to illustrate the generated field and provide insight to the relevance of different mechanism taken into account in the model. PACS 02.70.Dh; 43.35.+d; 42.62.-b